/*******************************************************************************
 * Copyright (c) 2000, 2005 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.draw2d;

import org.eclipse.draw2d.geometry.Point;

/**
 * Provides support for anchors which depend on a figure for thier location. 
 * @author hudsonr
 */
public abstract class AbstractConnectionAnchor
	extends ConnectionAnchorBase
	implements AncestorListener
{

private IFigure owner;

/**
 * Constructs an AbstractConnectionAnchor with the owner supplied as input.
 *
 * @since 2.0
 * @param owner  Owner of this anchor
 */
public AbstractConnectionAnchor(IFigure owner) {
	setOwner(owner);
}

/**
 * Adds the given listener to the listeners to be notified of anchor location changes.
 *
 * @since 2.0
 * @param listener   Listener to be added
 * @see  #removeAnchorListener(AnchorListener)
 */
public void addAnchorListener(AnchorListener listener) {
	if (listener == null)
		return;
	if (listeners.size() == 0)
		getOwner().addAncestorListener(this);
	super.addAnchorListener(listener);
}

/**
 * Notifies all the listeners of this anchor's location change.
 *
 * @since 2.0
 * @param figure  Anchor-owning Figure which has moved
 * @see org.eclipse.draw2d.AncestorListener#ancestorMoved(IFigure)
 */
public void ancestorMoved(IFigure figure) {
	fireAnchorMoved();
}

/**
 * @see org.eclipse.draw2d.AncestorListener#ancestorAdded(IFigure)
 */
public void ancestorAdded(IFigure ancestor) { }

/**
 * @see org.eclipse.draw2d.AncestorListener#ancestorRemoved(IFigure)
 */
public void ancestorRemoved(IFigure ancestor) { }

/** 
 * Returns the owner Figure on which this anchor's location is dependent.
 *
 * @since 2.0
 * @return  Owner of this anchor
 * @see #setOwner(IFigure)
 */
public IFigure getOwner() {
	return owner;
}

/**
 * Returns the point which is used as the reference by this AbstractConnectionAnchor. It
 * is generally dependent on the Figure which is the owner of this
 * AbstractConnectionAnchor.
 *
 * @since 2.0
 * @return  The reference point of this anchor
 * @see org.eclipse.draw2d.ConnectionAnchor#getReferencePoint()
 */
public Point getReferencePoint() {
	if (getOwner() == null)
		return null;
	else {
		Point ref = getOwner().getBounds().getCenter();
		getOwner().translateToAbsolute(ref);
		return ref;
	}
}

/**
 * Removes the given listener from this anchor. If all the listeners are removed, then
 * this anchor removes itself from its owner.
 *
 * @since 2.0
 * @param listener  Listener to be removed from this anchors listeners list
 * @see #addAnchorListener(AnchorListener)
 */
public void removeAnchorListener(AnchorListener listener) {
	super.removeAnchorListener(listener);
	if (listeners.size() == 0)
		getOwner().removeAncestorListener(this);
}

/**
 * Sets the owner of this anchor, on whom this anchors location is dependent.
 *
 * @since 2.0
 * @param owner  Owner of this anchor
 */
public void setOwner(IFigure owner) {
	this.owner = owner;
}

}
